Yes—using shift is generally fine on a star tracker, as long as you keep the shift amount and direction fixed during the exposure. A shifted image is essentially like using a larger image circle and cropping a different part of it, so the tracker itself does not care.

The main practical issue is not the shift mechanism, but the usual tracked-landscape problem: while the tracker follows the stars, the foreground will blur over a long exposure. A separate untracked exposure for the landscape and blending later is often the best approach.

One subtle point: if you shift upward, the parts of the frame farther from the tracker’s reference center can show slightly different apparent motion, so any star trailing toward the shifted edge/corners may be more noticeable if tracking is imperfect. But with a fixed shift, there’s no special complication beyond normal wide-angle tracked shooting.

So: fixed shift is OK; don’t change the shift angle mid-shot; and consider shooting the sky tracked and the foreground static as two frames.